state_machine

https://github.com/pluginaweek/state_machine

Ruby

Adds support for creating state machines for attributes on any Ruby class

StateMachine::Integrations::ActiveModel#add_callback

Creates a new callback in the callback chain, always inserting it
before the default Observer callbacks that were created after
initialization.

Source | Google | Stack overflow

Edit

git clone [email protected]:pluginaweek/state_machine.git
cd state_machine
open lib/state_machine/integrations/active_model.rb

Contribute

# Make a new branch
git checkout -b -your-name--update-docs-StateMachine--Integrations--ActiveModel-add_callback-for-pr

# Commit to git
git add lib/state_machine/integrations/active_model.rbgit commit -m "better docs for StateMachine::Integrations::ActiveModel#add_callback"

# Open pull request
gem install hub # on a mac you can `brew install hub`
hub fork
git push <your name> -your-name--update-docs-StateMachine--Integrations--ActiveModel-add_callback-for-pr
hub pull-request

# Celebrate!